72 

PALAZOZOIC CRINOIDS 
T the seventh and last of the ordinary monthly meet- 
ings of the Montreal Natural History Society for 
the season 1870-71 a communication on a Mineral Sili- 
cate injecting Palzeozoic Crinoids was made by Dr. T. 
Sterry Hunt. The author described a gray granular 
palaozoic limestone from New Brunswick, which had 
been examined by Dr. Dawson, and found to consist 
almost entirely of the comminuted remains of brachiopod 
and gasteropod shells, crustacea, and the joints and plates 
of crinoids, cemented with a little calcareous spar. The 
crinoidal remains were, however, found to have their pores 
filled with a peculiar silicate, which is exposed in relief 
when the surface of the limestone is attacked by an 
acid, and then appears as a congeries of small cylindrical 
rods or bars, anastomosing and forming a beautiful net- 
work which, under a magnifying glass, exhibits a frosted 
crystalline surface, and resembles the variety of aragonite 
known as flos ferrz. This silicate, which also fills small 
intersticesamong the other calcacereous fragments making 
up the limestone, is greenish in colour and forms about 
5 per cent. of the rock. Though insoluble in dilute acids, 
it is completely decomposed by strong acids, and is found 
to be a hydrous silicate of ferrous oxide and alumina, 
with some magnesia and a little alkali, closely allied to 
fahlunite and to jollyte. The results of its analysis will 
appear in S7/limanws Fournal for May. Dr. Hunt re- 
marked that this process of infiltration, by which the 
minute structure of these palzeozoic crinoids has been 
preserved, was precisely similar to that seen in the glau- 
conite casts of more modern foraminifera, and in the 
Eozéon of older times. This ancient calcacerous rhizo- 
pod, though most frequently preserved by serpentine, 
had been shown, both by himself in Canada and by 
Hoffmann in Bohemia, to be in some cases in- 
jected by silicate related in composition to that of these 
crinoids. The great class of silicates of which serpen- 
gine, loganite, pyfosclerite, fahlunite, and jollyte are mem- 
ers, are generally described as the results of pseudo- 
morphic changes of pre-existing silicates or carbonates ; 
but Dr. Hunt maintains them to be original aqueous 
depositions, similar in their origin to the related mineral 
glauconite ; a view now adopted by such investigators as 
Naumann, Scheerer, Giimbel, and Credner. These facts 
have an important bearing on the Eozdon Canadense of 
Dawson, the organic nature of which, though almost 
universally admitted by zoologists and mineralogists, is 
nevertheless still questioned by Messrs. King and Rowney. 
These gentlemen object that the ancient rocks in which 
Eozdéon is found are what are called metamorphic strata, 
which have been, according to them, subjected to pseudo. 
morphic changes, and therefore the Eozéon may be the 
result of some unexplained plastic force, which has 
fashioned the serpentine and other mineral silicates into 
forms so like those of foraminiferal organisms as to de- 
ceive the most practised observer. This was going back 
to the notions of those who, rather than admit that moun- 
tains had been formed beneath the sea, imagined that 
the fossil shells which they often contain were not the 
real shells of animals, but the result of some freak of 
nature. The argument of Messrs. King and Rowney 
that the Eozéon rock is a result of pseudomorphic altera- 
tion because it contains serpentine, is a begging of the 
question at issue, by asking us to admit that the presence 
of serpentine is an evidence of metamorphic change, 
which is denied. The specimens of this organic lime- 
stone, with its injected crinoids, differs from Eozéonal 
rock only in containing at the same time recognisable 
fragments of other organic remains, and in presenting in 
its injected portions the differences which distinguish the 
minute structure of acrinoid from that of a calcareous 
rhizopod. 
Principal Dawson has verified the observations of Dr. 
NATURE 

[May 25,1871 

Hunt by microscopic examinations. Crinoids in the fossil 
state are generally filled with carbonate of lime so as to 
obliterate their pores. The infiltrating silicate in the 
present case, however, shows, especially in decalcified 
specimens, that these ancient crinoids closely resembled 
in their minute structure the modern forms lately studied 
by Dr. W. B. Carpenter and Prof. Wyville Thomson, 
especially Comatula. The process of filling up the porous 
calcareous skeleton of the crinoids has been clearly shown 
to be prior to the cementing and consolidation of frag- 
mentary limestone. 
Tothis we may add that fragments of the calcareous 
skeleton of Echinoderms infiltrated with silicates have 
been detected by Dr. Carpenter, together with Polystomelle 
and many other foraminifera similarly infiltrated, in Capt. 
Spratt’s dredgings from the Aigean. On placing these 
fragments in dilute acid, the calcareous network of which 
Dr. Carpenter nearly thirty years ago showed the skele- 
tons of all Echinoderms to be made up, is dissolved 
away; and a perfect model is left in green or ochreous 
silicates, of the sarcodic network, with which, in the 
living state, the interspaces of the calcareous network are 
occupied. Dr. Carpenter, however, objects to the term 
“infiltration ” as expressive of the process by which the 
replacement of the sarcodic substance by silicates has 
taken place. As this process is going on at the present 
time on the ordinary sea-bottom, he thinks that it can 
only be attributed to a process of “ substitution,” in which 
the decomposition of the sarcodic substance performs an 
essential part. Whatever may be regarded as chemically 
the most probable explanation of the replacement, it will 
be obviously the same for the ancient as for the modern 
examples of the process. 



NOTES 
At the Anniversary Meeting of the Royal Geographical 
Society held on Monday last, the address of the retiring president, 
Sir R. I. Murchison, was read by the secretary, Mr. Clements 
Markham, Sir Roderick thus closing an occupancy of the pre- 
sidential chair extending over sixteen years. He is succeeded 
by Sir Henry Rawlinson. The Founder’s Medal was on the 
same occasion awarded to Sir R. Murchison in recognition of the 
eminent services he had rendered to geography during his long 
connection with the society, in the course of which he had been 
associated with every exploring expedition for the last thirty 
years. The Patron’s or Victoria Medal was presented to Dr. A. 
Keith Johnston for his long-continued and successful services in 
advancing geography. We regret to find that the retiring presi- 
dent found it necessary to send a letter to the secretary forbidding 
any hope that he would be able very soon to take an active part 
in the proceedings of the society, his progress towards complete re- 
covery being slow. At the annual dinner which followed, the Dean 
of Westminster expressed a hope that we might yet see the founda+ 
tion of a professorship of geography at each of the universities, 
ArT the Anniversary Meeting of the Linnean Society, held yes- 
terday, Mr. Bentham delivered his annual address, which we 
hope to have an early opportunity of giving to our readers. Mr. 
Bentham was re-elected to the office of President, Mr. Wilson 
Saunders of Treasurer, and Messrs. F. Currey and H. T, 
Stainton of Secretaries, and the following gentlemen, in addi- 
tion, were elected members of the Council for the ensuing year : 
Mr. John Ball, F.R.S., Mr. Alfred W. Bennett, Mr. J. J. 
Bennett, F.R.S., Mr. George Busk, F.R.S., Mr. F. Ducane 
Godman, Dr. J. D. Hooker, F.R.S., Prof. M. A. Lawson, 
Mr, Henry Lee, Mr. S, J. A. Salter, F.R.S., Dr. J. Lindsay 
Stewart, and the Rey. Thomas Wiltshire. 
THE Board of Natural Science Studies for the Natural Science 
Tripos of the University of Cambridge has issued a set of sche- 
dules indicating the subjects to which the examination in 1872 

